Are there any guidelines on USCIS website, or anywhere else, on how long before the 5-year clock runs its course can one submit N 400? My GC was approved in May 2005, and I was wondering if I should wait till May 2010 before fililng the application or go ahead now? USCIS forms mention one has to be a perm res for 5 years before applying, but I have seen posts here that suggest otherwise. Any thoughts?